A composite article includes a substrate and a powder-derived composite coating on the substrate. The composite coating includes discrete regions of a first material and discrete regions of a second material. At least one of the first material or the second material is a chemical precursor.

In a surface-coated cutting tool, an A layer made of an (Al.sub.1-xTi.sub.x)N layer (0.35≦x≦0.6 by an atom ratio) and a B layer made of a (Al.sub.1-y-zTi.sub.ySi.sub.z)N layer (0.35≦y≦0.6 and 0.01≦z≦0.1 by an atom ratio) are layered on a surface of a tool body in which at least a cutting edge is made of a cBN sintered body. A layer thickness ratio of the A layer and the B layer (t.sub.B/t.sub.A) is 2 to 5, an X-ray diffraction intensity ratio I(200)/I(111) as the entire hard coating layer is more than 3 and 12 or less, a full width at half maximum of a peak of I(200) is 0.3 to 1.0, the I.sub.A(200)/I.sub.A(111) of the A layer is 2 to 10, and a full width at half maximum of the peak of the I.sub.A(200) is 0.3 to 1.0.

In a surface-coated cutting tool, an A layer made of an (Al.sub.1-xTi.sub.x)N layer (0.35≦x≦0.6 by an atom ratio) and a B layer made of a (Al.sub.1-y-zTi.sub.ySi.sub.z)N layer (0.35≦y≦0.6 and 0.01≦z≦0.1 by an atom ratio) are layered on a surface of a tool body in which at least a cutting edge is made of a cBN sintered body. A layer thickness ratio of the A layer and the B layer (t.sub.B/t.sub.A) is 2 to 5, an X-ray diffraction intensity ratio I(200)/I(111) as the entire hard coating layer is more than 3 and 12 or less, a full width at half maximum of a peak of I(200) is 0.3 to 1.0, the I.sub.A(200)/I.sub.A(111) of the A layer is 2 to 10, and a full width at half maximum of the peak of the I.sub.A(200) is 0.3 to 1.0.

A method of altering a surface of a ceramic matrix composite to aid in nodule removal is described. A fiber preform comprising a framework of ceramic fibers is heated to a temperature at or above a melting temperature of silicon. During the heating, the fiber preform is infiltrated with a molten material comprising silicon. After the infiltration, the fiber preform is cooled, and the infiltrated fiber preform is exposed to a gas comprising nitrogen during cooling. Silicon nitride may be formed by a reaction of free (unreacted) silicon at or near the surface of the infiltrated fiber preform with the nitrogen. Thus, a ceramic matrix composite having a surface configured for easy nodule removal is formed. Any silicon nodules formed on the surface during cooling may be removed without machining or heat treatment.

A method of altering a surface of a ceramic matrix composite to aid in nodule removal is described. A fiber preform comprising a framework of ceramic fibers is heated to a temperature at or above a melting temperature of silicon. During the heating, the fiber preform is infiltrated with a molten material comprising silicon. After the infiltration, the fiber preform is cooled, and the infiltrated fiber preform is exposed to a gas comprising nitrogen during cooling. Silicon nitride may be formed by a reaction of free (unreacted) silicon at or near the surface of the infiltrated fiber preform with the nitrogen. Thus, a ceramic matrix composite having a surface configured for easy nodule removal is formed. Any silicon nodules formed on the surface during cooling may be removed without machining or heat treatment.

A method for manufacturing a pillar-shaped honeycomb structure filter including preparing a pillar-shaped honeycomb structure having a plurality of first cells and a plurality of second cells that are alternately arranged adjacent to each other with a porous partition wall interposed therebetween; adhering ceramic particles containing 50% by mass or more in total of one or two selected from SiC and SiN to a surface of the first cells; and performing a heat-oxidation treatment on the pillar-shaped honeycomb structure in which the ceramic particles are adhered to the surface of the first cells to form a porous film comprised of the ceramic particles having an oxide film thereon so as to satisfy: (1) 0.05≤T≤0.5; (2) 0.05≤T/D50; and (3) 4≤{(W.sub.1−W.sub.0)/W.sub.0×100}/D50.

A method for manufacturing a pillar-shaped honeycomb structure filter including preparing a pillar-shaped honeycomb structure having a plurality of first cells and a plurality of second cells that are alternately arranged adjacent to each other with a porous partition wall interposed therebetween; adhering ceramic particles containing 50% by mass or more in total of one or two selected from SiC and SiN to a surface of the first cells; and performing a heat-oxidation treatment on the pillar-shaped honeycomb structure in which the ceramic particles are adhered to the surface of the first cells to form a porous film comprised of the ceramic particles having an oxide film thereon so as to satisfy: (1) 0.05≤T≤0.5; (2) 0.05≤T/D50; and (3) 4≤{(W.sub.1−W.sub.0)/W.sub.0×100}/D50.

A method to produce a protective surface layer having a predetermined topography on a ceramic matrix composite is described. The method includes applying a slurry layer to a surface of a fiber preform, and drying the slurry layer to form a particulate layer. A surface of the particulate layer is machined to improve surface smoothness and to form a machined surface. A ceramic tape is attached to the machined surface, and a tool comprising one or more features to be imprinted is placed on the ceramic tape, thereby forming a compression assembly. Heat and pressure are applied to the compression assembly to consolidate and bond the ceramic tape to the machined surface, while the one or more features of the tool are imprinted. Thus, a protective surface layer having a predetermined topography is formed.

A method to produce a protective surface layer having a predetermined topography on a ceramic matrix composite is described. The method includes applying a slurry layer to a surface of a fiber preform, and drying the slurry layer to form a particulate layer. A surface of the particulate layer is machined to improve surface smoothness and to form a machined surface. A ceramic tape is attached to the machined surface, and a tool comprising one or more features to be imprinted is placed on the ceramic tape, thereby forming a compression assembly. Heat and pressure are applied to the compression assembly to consolidate and bond the ceramic tape to the machined surface, while the one or more features of the tool are imprinted. Thus, a protective surface layer having a predetermined topography is formed.

A coating according to an exemplary embodiment of this disclosure, among other possible things includes a bond coat including gettering particles and diffusive particles dispersed in a matrix; a top coat disposed over the bond coat, the top coat includes metal silicate particles; and an intermediate layer between the bond coat and the top coat. The intermediate layer includes hafnium silicate particles and matrix. A concentration of metal silicate in the intermediate layer is less than a concentration of metal silicate in the top coat. An article is also disclosed.